The intestinal microbiome is the set of living microorganisms and their genes (bacteria, fungi, viruses, protozoa…) that reside in our intestine and that are increasingly being associated with more health problems when their balance is altered, and research has This population of microbes has now been linked to multiple pathways involved in the pathogenesis of Parkinson’s disease, a chronic pathology that affects the central nervous system and causes everything from motor symptoms (tremors, rigidity…) to emotional and cognitive disorders.
A previous study had already linked the bacterial composition of the intestinal flora with this and other neurodegenerative diseases, such as Alzheimer’s or amyotrophic lateral sclerosis (ALS), but this study carried out by scientists from the University of Alabama at Birmingham (UAB) is the The largest study on the subject carried out at the highest resolution and has found a wide imbalance in the composition of the microbiome in patients with Parkinson’s. The researchers used metagenomics (the study of all genes in an environment) to study genetic material from the stool microbiome of people with Parkinson’s and other neurologically healthy individuals who served as controls.
“We found evidence for multiple mechanisms that we know are related to Parkinson’s disease, but we didn’t know that they were also occurring in the gut and that they are orchestrated by the microbiome,” said Haydeh Payami, a professor in the Department of Neurology at the School of Marnix E. Heersink MD and lead author of this research, whose results have been published in Nature Communications and show that the Parkinson’s metagenome is indicative of a microbiome that promotes this disease.
Imbalance in the microbiome favors neurodegenerative events
Payami and colleagues recruited 490 people with Parkinson’s disease and 234 healthy individuals (slightly more than half were men, with a predominance of those older than 50 years), all of whom resided in the Deep South region of the United States, which He ruled out that the composition of their microbiome was influenced by geographical or cultural factors.
“More than 30% of microorganisms and bacterial genes and pathways tested have altered abundances in Parkinson’s disease, indicating a general imbalance”
The team studied 257 species of organisms in the microbiome and the analysis indicated that 84 of them – more than 30% – were associated with Parkinson’s disease. “Of the 84 species associated with Parkinson’s disease, 55 were abnormally high in abundance in people with Parkinson’s disease and 29 became depleted,” Payami explained. “We found that more than 30% of microorganisms and bacterial genes and pathways tested have altered abundances in Parkinson’s disease, indicating a pervasive imbalance.”
The researchers found an excess of opportunistic pathogens and immunogenic components, suggesting the presence of infection and inflammation. They also noted that there was a shortage of neuroprotective molecules and anti-inflammatory components, making recovery difficult. At one end of the spectrum, Bifidobacterium dentium multiplied by seven, Actinomyces oris by 6.5, and Streptococcus mutans by six. At the other end of the spectrum, Roseburia intestinalis was reduced 7.5 times and Blautia wexlerae 5 times. Overall, 36% of the Parkinson’s disease-associated species had a greater than two-fold change in abundance, reflecting a 100% to 750% increase or decrease in Parkinson’s disease compared to the Parkinson’s disease group. healthy control.
“This study created a large data set with the highest resolution currently feasible and made it public without restrictions to promote open science,” Payami said. “It includes extensive metadata on 490 people with Parkinson’s, the largest Parkinson’s cohort with microbiome data, and a unique cohort of 234 neurologically healthy elderly, which can be used in a wide range of studies. We have shown that there is a pervasive imbalance in the Parkinson’s metagenome, creating an environment that is permissive for neurodegenerative events and prohibitive for recovery.”
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